The present invention relates to a printing apparatus that prints recording paper by an electrophotographic image forming method or the like, and a method for controlling the printing apparatus.
Some of this type of printing apparatus have sped up the printing process, so a plurality of print jobs can be executed one after another.
In order to maintain such a high speed printing process, it is necessary to continuously execute a plurality of jobs without interruption. To this end, for example, the technique disclosed in JP 2000-330741A increases the duration for which a printing operation can be carried out continuously by omitting the initialization operation of the apparatus that is performed after each job, and performing print data management on a per job basis with a configuration in which jobs and print data are managed separately by a job management unit and a print data management unit, respectively, and a printing operation is continued if both a job to be printed and the print data are present during the printing operation, and an instruction to stop the printing operation is outputted only if it is necessary to perform an initialization operation after a stop request is made or a printer parameter is changed.
A printing apparatus usually has a plurality of paper feed cassettes, so recording papers of given sizes can be placed and loaded in the paper feed cassettes. When recording paper is placed and loaded in a paper feed cassette, the size of the recording paper loaded in the paper feed cassette is inputted/instructed. And, when executing a print job, the paper feed cassette that contains the recording paper of the size set by this print job is selected, and the recording paper is drawn from this paper feed cassette to feed the paper.
However, if a wrong size is inputted/instructed when inputting/instructing the size of the recording paper that has been loaded in the paper feed cassette, then, even if the paper feed cassette is selected according to the size set by the print job, the paper feed cassette feeds recording paper having a size different from that set by the print job, resulting in defective printouts.
Also, if the size of recording paper is different from that set by a print job, the timing of conveying the recording paper is shifted for example, and a conveyance failure or jam of recording paper is likely to occur. If such an event occurs, the print job stops immediately, and the print job cannot be restored for a long time until that event is resolved. Particularly when a plurality of print jobs are queued, the printing of all the print jobs is delayed, and it is therefore impossible to achieve a high speed printing process.
Alternatively, it is also possible to conceive a configuration in which the size of the recording paper fed from a paper feed cassette is detected, and a printing process is stopped immediately when the detected size of the recording paper is different from the size set by the print job. However, in this case also, the print jobs are stopped, and the printing of all the print jobs is delayed.
Further, even if the technique disclosed in JP 2000-330741A can omit the initialization operation that is performed before each job, it cannot solve the stopping of print jobs caused by such a mismatch in the recording paper size.